AngularJS throttle service

/**
 * Throttling callbacks with specified delay.
 * inspired by @link http://benalman.com/projects/jquery-throttle-debounce-plugin/
 */
.factory('Throttle', ['$rootScope', function throttle($rootScope)
{
	var allTimeouts = {};
	$rootScope.$on('$routeChangeStart', function() {
		for (var i in allTimeouts) {
			clearTimeout(allTimeouts[i]);
		}
		allTimeouts = {};
	});

	/**
	 * noTrailing is to prevent execution one last time after all invokation stopped
	 */
	return function (delay, noTrailing, $scope, callback) {
		var unique = Math.round(Math.random() * 1e15),
			timeoutId,
			lastExec = 0;

		if (typeof noTrailing != 'boolean')
		{
			callback = $scope;
			$scope = noTrailing;
			noTrailing = undefined;
		}

		// this wrapper will be invoked by consumers
		function wrapper()
		{
			var me = this,
				elapsed = (+new Date) - lastExec,
				args = arguments;

			timeoutId && clearTimer();

			if (elapsed > delay) {
				exec();
			}
			else if (! noTrailing)
			{
				timeoutId = setTimeout(function () {exec()}, delay - elapsed);
				storeTimer();
			}

			// Executing given function
			function exec()
			{
				lastExec = +new Date;
				clearTimer();
				callback.apply(me, args);
				if (! $scope.$$phase) {
					$scope.$digest();
				}
			}

			function storeTimer()
			{
				allTimeouts[unique] = timeoutId;
			}
			function clearTimer()
			{
				clearTimeout(timeoutId);
				allTimeouts[unique] = timeoutId;
			}
		}

		return wrapper;
	};
}])